[GHC] #15139: EmptyCase produces incorrect SrcSpans

[GHC]

#15139: EmptyCase produces incorrect SrcSpans
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.2
  (Parser)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4685
       Wiki Page:                    |
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Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"78db41eaa806206001b80b3d225cd254435a2f83/ghc" 78db41e/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="78db41eaa806206001b80b3d225cd254435a2f83"
 Use correct source spans for EmptyCase

 Summary:
 The parser's calculation of source spans for `EmptyCase`
 expressions was a bit off, leading to some wonky-looking error
 messages. Easily fixed with some uses of `comb3` and `sLL`.

 Test Plan: make test TEST=T15139

 Reviewers: bgamari, simonpj

 Reviewed By: simonpj

 Subscribers: simonpj, rwbarton, thomie, mpickering, carter

 GHC Trac Issues: #15139

 Differential Revision: https://phabricator.haskell.org/D4685
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15139#comment:2>
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